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N340 Remark Code: Subscriber Birth Date Missing/Invalid

N340 means the date of birth of the subscriber, the person who holds the insurance policy, was missing, incomplete, or invalid. The payer could not match the policyholder in its enrollment records.

Quick facts

Code
N340 (RARC N340)
Status
Active In use since December 2, 2004.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): A correctable subscriber data problem. The provider fixes the birth date and resubmits; the patient is not billed for this adjustment.
Official description
Missing/incomplete/invalid subscriber birth date.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N340 means

Every claim names a subscriber, the person whose policy covers the patient. When the patient is a spouse or child, the subscriber is someone else, and the payer uses that person’s name, member ID, and birth date to locate the policy. N340 means the subscriber’s birth date on the claim was blank, partial, or did not match the payer’s enrollment file.

N340 typically accompanies CARC 16. If the mismatch prevents the payer from finding the policy at all, it can come with CARC 31 or CARC 140.

Common causes

  • The dependent patient’s birth date was entered in the subscriber’s field.
  • Registration captured the subscriber’s name but left the birth date blank because the subscriber wasn’t present.
  • The subscriber changed, for instance when a child moved to the other parent’s plan, and the old policyholder’s date stayed on file.
  • The payer’s enrollment record has a different birth date due to an employer data error.

How to fix it

  1. Run an eligibility inquiry that returns the subscriber’s details and compare the birth date with your record.
  2. If you lack the date, contact the patient or guarantor. Don’t guess based on the patient’s age.
  3. Correct box 11a (or the 837P subscriber section) and confirm the relationship-to-insured field in box 6 is right.
  4. Resubmit a corrected claim with frequency code 7, or a new claim if the original was rejected up front.
  5. When the payer’s file is wrong, the subscriber needs to fix it with the employer or plan. Note the account so the claim can be rebilled once enrollment is updated.

How to prevent it

At registration, collect the subscriber’s full name, birth date, and relationship as separate required fields whenever the patient isn’t the policyholder. Eligibility checks before each visit catch mismatches early. Our guide to eligibility and COB denials covers subscriber data problems in more depth.

Codes that may appear with N340

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): Information is missing or wrong; N340 identifies the subscriber's date of birth.
  • CO-31 (Patient cannot be identified as our insured.): The patient cannot be identified as the payer's insured, which a wrong subscriber birth date can cause.
  • CO-140 (Patient/Insured health identification number and name do not match.): The health ID and name do not match, often part of the same subscriber data problem.
  • N329 (Missing/incomplete/invalid patient birth date.): Used when the patient's birth date is wrong rather than the subscriber's.
  • N327 (Missing/incomplete/invalid other insured birth date.): Covers the birth date of the insured on the patient's other coverage.
  • N382 (Missing/incomplete/invalid patient identifier.): Addresses a missing or invalid patient identifier.

N340 FAQ

Where does the subscriber's birth date go?

On the CMS-1500 it is in box 11a, the insured's date of birth. On the 837P it is in the subscriber demographic information.

What if the patient is the subscriber?

Then the patient's and subscriber's birth dates should be identical. Many systems handle this automatically, but a manual override can cause them to differ.

Will the payer accept an ID card as proof?

Most cards do not show the subscriber's birth date. Verify it with the patient or through an eligibility check instead.